Engine safety device



July 12, 1955 w. B. THOMAS ENGINE SAFETY DEVICE Filed Aug. 15

E/SG

INVENTOR. h. 5. Thomas Afforneu.

Patented July 12, 1955 2,712,813 ENGENE SAFETY DEVICE William B. Thomas, Ada, Okla. Application August 15, 1951, Serial No. 242,022 3 Claims. (Cl. 123-4114) This invention relates to improvements in internal combustion engines and more particularly, but not by way of limitation, to a safety device for internal combustion engines normally operated at substantially con stant speeds and loads.

As it is well known, particularly in the oil industry, internal combustion engines are utilized to a large extent to drive various types of equipment such as generators and oil well surface pumping equipment in such a manner that the engines normally operate at constant speeds and loads. Frequently, the engines are operated in locations where it is impractical to provide an operator to continuously observe the operations thereof. In the event of a failure in the engine, such as a broken piston or the like, the engine will become overloaded and seriously damaged due to the fact that no one will be present to shut down the engine. Furthermore, the equipment being driven by such an internal combustion engine frequently becomes partially damaged and overloads the engine, and since no one is present to shut down the engine, the equipment is very seriously damaged, entailing excessive maintenance and replacement costs.

Several systems have been devised to shut off an internal combustion engine in the event of a governor failure or the like to prevent the engine from attaining an excessive speed and running away. For example, Patent No. 2,131,264 issued to Walter E. Benjamin on September 27, 1938, discloses a vacuum operable device connected to the carburetor of an internal combustion engine between the venturi tube and the butterfly valve. The vacuum operable device is operated upon an increased vacuum in the carburetor outlet to open a switch interposed in the ignition circuit and shut off the engine when the vacuum reaches a predetermined reading. In this manner, the vacuum operable device is actuated when the governor fails and causes a complete opening of the butterfly valve. The vacuum operable device utilizes a diaphragm interconnected to the ignition circuit in such a manner that an increased vacuum in the carburetor moves the diaphragm and tends to retain the diaphragm in such a position that the ignition circuit will be opened to shut down the engine. A helical spring tends to retain the diaphragm in such a position that the ignition circuit will be closed. Therefore, the diaphragm and the conduit interconnecting the vacuum operable device to the carburetor must at all times be air tight to provide efiicient operation of the device. In the event of a failure of the diaphragm or a leak in the interconnecting conduit, an increased vacuum in the carburetor would have no effect on the diaphragm and the device would become inoperable. Furthermore, this condition of the device could not be ascertained by a cursory examination. In addition, same means must be provided to retain the ignition circuit in an open condition after the vacuum operable device has been actuated by an increased vacuum in the carburetor. Otherwise, the ignition circuit would be closed immediately subsequent to the opening thereof due to the decrease in vacuum in the carburetor provided by the deceleration of the engine.

The present invention contemplates a safety device having a housing interconnected to the intake manifold of an internal combustion engine between the butterfly valve and the engine intake valves. A diaphragm is interposed in the housing and is interconnected to the engine ignition circuit in such a manner that upon a decrease in vacuum in the engine manifold the diaphragm is moved in one direction by the action of a suitable spring to interrup the ignition circuit and shut oi the engine. The diaphragm is continually urged in one direction by said spring to interrupt the ignition circuit. Therefore, in the internal combustion engines having a water cooling system. The valve is adapted to be automatically opened when the engine is shut down to drain the radiator of the engine, thereby precluding the necessity of using antifreeze in the engine cooling system during the winter months.

An important object of this invention is to prevent an internal combustion engine from becoming overloaded.

Another object of this invention is to provide a safety device for an internal combustion engine adapted to shut down the engine upon a decrease in vacuum in the intake manifold of the engine.

manifold of the engine.

A further object of this invention is to increase the safe operation of internal combustion engines.

A still further object of this invention is to provide ly manufactured.

Other objects and advantages of this invention will be evident from the following detailed description, read in conjunction with the accompanying drawings, which illustrate my invention.

In the drawings:

Figure l is a partial diagrammatic view of an internal combustion engine carburetor and intake manifold.

Figure 2 is an elevational view of a novel safety device, shown partially in section for clarity.

Fig. 1, reference character 2 designates an intake manifold providing the usual inlet passageway for the air and gas mixture to the intake valves (not shown) of an internal combustion en ine (not shown). The manifold 2 also communicates with the outlet 4- of a suitable carburetor (not shown). A venturi 6 is provided in the carburetor outlet 4 in the usual manner. A butterfly or throttle valve 8 is also provided in the carburetor outlet 4 and in upwardly spaced relation to the venturi 6. A suitable conduit 10 is interconnected to the intake manifold 2 between the butterfly valve 3 and the engine intake valves in such a manner that the vacuum existing in the intake manifold 2 will also be present in the con- U The conduit Iii is provided to interconnect a 12 (Fig. 2)

duit it novel safety device generally indicated at to the intake manifold 2.

The safety device 12 comprises a sectional housing or casing 14 having substantially duplicate half portions or sections 16 and i8. Duplicate circumferential flanges 2d and 22 are provided on the portions 16 and 18 respectively to facilitate the interconnection thereof by suitable bolts 24. A flexible diaphragm 26 is provided in the housing 14 and has its outer flanges 2% and 22, thereby supporting the diaphragm 26 and providing an efficient seal between the portions 16 and 18. The diaphragm 26 therefore divides the casing 14 into two chambers 28 and 3'3 for purposes as will be hereinafter set forth.

A threaded aperture tion of the section or half to receive the outer end 34 fore apparent that vacuum changes in 32 is provided in the central porportion 16 of the housing 14 of the conduit iii. it is therethe intake manifold 2 will be transmitted through the conduit to the chamber 23 and react on the diaphragm 26 to either pull the diaphragm 26 downwardly or release the diaphragm, depending upon the extent of vacuum in the intake manifold 2. As it is Well known, the variations in vacuum in the intake manifold of a multi-cylinder engine are comparatively slight during constant speed and load of the engine. Therefore, when the safety device 12 is being used on multi-cylinder engines, a simple surge tank 36 may be interposed in the conduit 10 to dampen the effect of the vacuum changes on the diaphragm 26 as will 7 be more fully hereinafter set forth.

A stem or rod 38 extends through the diaphragm 26 and is secured thereto by suitable reinforcing plates 40 and 42 in the usual manner. The stem 38 extends upwardly through a threaded aperture 44 provided in the upper section 18 of the housing 16. A tubular guide 46 is secured in the threaded aperture 44 around the stem 33 to retain the stem 38 in vertical alignment during movement thereof as will be hereinafter set forth. The stem 38 is of such a size to slide freely through the guide 46.

A suitable nut 48 is threadedly secured on the upper portion 50 of the stem 38m anchor the upper end of a helical spring 52. The spring 52 surrounds the stem 38 and is anchored at its lower end to the upper section 18 of the housing 14. it will be apparent that the spring 52 constantly urges the stem 38 and diaphragm 26 upwardly against the action of the vacuum in the chamber 28 and intake manifold 2, as will be hereinafter more fully set forth. The position of readily adjusted on the stem 38 to vary the tension of the spring 52. A bracket 54 is also secured to the upper portion 50 of the stem 33 and in upwardly spaced relation to the nut 48. The bracket 54 is preferably secured to the stem 33 by a suitable set screw 56, thereby facilitating vertical adjustment ing arm 53 is carried by the bracket 54 and extends transversely therefrom to operate a switch generally indicated at 69.

The switch is supported by a brace 62 on the upper section 18 of the housing 14 in such a position to be normally disposed opposite the bracket 54 and switch actuating arm 58. Two stationary contact arms 64 and 66 are provided on the switch 60 in vertically spaced relationship and are electrically interconnected by suitable leads 68. The leads 68 are interconnected (not shown) to the magneto (not shown) of the internal combustion engine ignition circuit (not shown) in a well known manner to ground out the magneto and interrupt the ignition circuit as will be hereinafter set forth. A movable contact ar.. 70 is provided'on the switch 60 between the stationary contact arms 64 and 66. An electrical lead 72 is connected at one end to the movable arm 70 and at its opposite end to any desired grounding point to provide a ground for the arm 76 for purposes as will edge clamped between the I the nut 48 may be thereof. A suitable switch actuat ture 86 and preclude be hereinafter set forth. The arm 70 is preferably spring loaded (not shown) and biased toward the upper stationary contact arm 64 in such a manner that the arm 70 will be automatically bent upwardly into contact with the arm 64 when released by the switch actuating arm 58.

A valve generally indicated at 76 is secured in any suitable manner above the stem 38. The valve 76 comprises a substantially cylindrical valve body 78 having an inlet conduit St and an outlet conduit 82 connected thereto. The inlet conduit 86 is connected at its opposite end to the drain connection (not shown) of the engine radiator (not shown). The outlet conduit 82 leads to any desired disposal (not shown). A valve member 84 is reciprocally disposed in the valve body 78 and is adapted to alternately open and close an aperture 86 which provides communic tion between the inlet 86 and outlet 32. The valve member 84 is carried by a stem E53 extending downwardly through the lower end of the valve body 78 in aligned relationship with the stem 38 of the safety device 12. A suitable packing gland 90 is provided around the stem 83 to preclude leakage of fluid from the valve body '78. A helical spring 92 surrounds the stem 88 below the valve body 78 to normally retain the valve member 84 in a closed position over the aperdraining of the engine radiator (not shown). The upper end of the spring 92 is anchored to the valve body 78 and the lower end thereof is anchored to a flange 94 provided on the lower end 96 of the stem 38. it will be apparent that the lower end 96 of the stem 38 is disposed in upwardly spaced relation to the upper end 97 of the stem 38 in such a manner that thestem 38, when moved upward, will not contact the valve stem 88 until the switch actuating arm 58 has completely released the switch arm 79.

Operation As previously safety device 12 on an internal combustion engine normally operating at a substantially constant speed and load. During such normal operation, the vacuum existing in the intake manifold 2 will be transmitted through the conduit 10 and chamber 28 of the housing 14 to exert a downward pull or force on the diaphragm 26 substantially equal to the upward force imposed thereon by the spring 52 through the medium of the nut 48 and stem 38. Therefore, the diaphragm 26 will assume a substantially horizontal position as shown in Fig. .2. In this position of the diaphragm 26, the switch actuating arm 53 is in such a position to retain the movable switch arm 70 out of contact with either of the stationary contacts 64 or 66. Therefore, electrical energy cannot flow from the leads 68 to the lead 72 and the ignition circuit will not be interrupted. It will also be noted that the upper end 97 of the stem 38 is disposed below the lower end 96 of the valve stem 88, thereby permitting the spring 92 to retain the valve member 84 in closing relationship.

' over the aperture 86.

During the normal fluctuations in load and speed of the engine, and hence relatively small fluctuations in the vacuum in the intake manifold 2, the movable switch arm 70 will be moved only a small extent and will not be moved into contact with either of the stationary contacts 64 or 66. Furthermore, the stem 38 will not be moved upwardly a sufficient distance to actuate the valve member 84. In the event of small, butsudden, load or speed changes of the engine, and hence sudden variations in vacuum in the manifold 2, the effect of the vacuum changes will be minimized by the surge chamber 36 to preclude movement of the diaphragm 26 a suificient distance to actuate the switch 60. 1

In the event the internal combustion engine becomes overloaded, or the engine attempts to reach an excessive speed and run away, the vacuum in the intake manifold 2 decreases.

through the conduit 10 to the chamber set forth, it is contemplated to use the r This vacuum change will be transmitted 28 to partially release the downward pull or force on the diaphragm 26. The spring 52 will then force the stem 38 and diaphragm 26 upwardly to release the S'.'.'ltCl'1 actuating arm 58 from the movable switch arm 70. Whereupon, the arm 70 is automatically bent upward into contact with the arm 64 to provide electrical communication between the leads 68 and 72 and ground out the magneto. The ignition circuit will thereby be interrupted or broken to stop the engine. It will be noted that as the engine slows down, the vacuum in the manifold 2 will be further decreased to more completely release the diaphragm 26 and permit further upward movement of the stem 38 by the action of the spring 52.

\Vhen the engine is substantially or completely stopped, the upper end 97 of the stem 38 will be moved upward by the spring 52 into contact with the lower end 96 of the valve stem 88 to remove the valve member 8 from the aperture 86. The liquid utilized in the engine cooling system will then be drained through the conduit 80, valve body 78 (including the aperture 86), and conduit 82. It will be apparent that the valve 76 is utilized on engines having a liquid cooling system, as contrasted with air cooled engines, and that the valve 76 will be connected to the cooling system only during the winter months to assure that the engine will be drained when stopped. In this manner, water may be used in the engine cooling system even during extremely cold weather.

It will be noted that the magneto will be grounded out when the engine has been stopped. Therefore, a manually operated switch (not shown) should be inter posed in either the wire 68 or wire 72 which may be opened when the switch 60 is closed to free the magneto and permit starting of the engine. When the engine has attained normal speed, the switch 60 will be opened, therefore, the manual switch should again be closed and left closed to permit operation of the safety device 12.

The lower stationary contact 66 is an additional safety feature. in the event the spring 52 should break, the vacuum in the chamber 28 will pull the diaphragm 26 further downward. The stem 38 and switch actuating arm 58 will thereby be moved downward to bend the arm 70 into contact with the lower contact arm 66. Electrical communication will th reby be established between the leads 63 and 72 to ground out the magneto and interrupt the ignition circuit, whereupon the engine will be stopped.

it will be apparent to those skilled in the art that the switch 60 may be slightly modified and interposed directiy in the ignition circuit, in the event the ignition circuit of the engine is not provided with a magneto. For example, the switch 60 may be replaced with a push button type switch (not shown), and the push button switch interposed directly in the ignition circuit. In this manner, the actuating arm 58 would operate the push button switch upon a decrease in vacuum in the ignition circuit in substantially manifold 2 to break the the same manner as previously described.

As previously set forth, the simple surge tank 36 may be used when the safety device 12 is being utilized on a multi-cylinder engine, since the normal vacuum changes in the intake manifold 2 will be comparatively slight. However, when the device 12 is being utilized on a single cylinder engine, and particularly on a four stroke single cylinder engine, the normal vacuum changes in the manifold 2 will be substantial and must be dampened to preclude excessive wear of the diaphragm 26, as well as inadvertent actuation of the switch 60.

To accommodate and dampen such substantial vacuum changes, I contemplate a novel surge tank generally indicated at 100 and illustrated in detail in Fig. 3. The surge tank 100 comprises a substantially cylindrical housing 102 divided into three (but not limited thereto) chambers 104, 106 and 108 by a pair of partitions 110 and 112. An aperture 114 is provided in each of the partitions 110 and 112 to establish limited communication between the adjacent chambers. In addition, an. aperture 116 is provided in the central portion of one end plate 118 of the housing 102. A conduit 120 is connected to the end plate 118 in any suitable manner, such concentrically around the aperture 116,.

housing. 14 to provide communication between the aperture 116 and the housing 14 below the diaphragm 26 for purposes as will be hereinafter set forth.

Referring again to Fig. 3, the opposite end plate 122 of the housing 102 is provided with an internally threaded coupling 124 in the central portion thereof. A novel bushing 126 is threadedly secured in the coupling 124 and is threaded at its outer end 128 for interconnection (not shown) with the conduit 10 to provide communication between the chamber 194 and the intake manifold 2. A square or hexagonal shaped turning flange 130 is also provided on the bushing 126 in the usual manner. The inner end 132 of the bushing 126 is disposed in the chamber 104 and is provided with an inwardly extending circumferential shoulder 134. The shoulder 134 is slightly slightly enlarged for clarity) is provided transversely in the bushing 126 in spaced relation to the valve seat 134 to provide very limited continuous communication between the interior of the bushing 126 and the chamber 104. Suitable stops 142 are secured in the bushing 126 to limit the opening movement of the ball 136.

As it is well known, the suction stroke of a single cylinder four stroke engine occupies only one fourth of each cycle of operation. Therefore, a vacuum will be created in the intake manifold 2 only during one fourth of each cycle; during the remaining three fourths of each cycle, the pressure in the manifold 2 will be approximately atmospheric. During the suction stroke of the engine, the vacuum created in the intake manifold 2 will be transmitted through the conduit 10 and bushing 126 to remove the ball 136 from the seat 134, thereby providing substantially unrestricted communication between the chamber 104 and the manifold 2 through the aperture 138, bushing 126 and conduit 10. The vacuum in the manifold 2 is thereby substantially reproduced in the chamber 104. Upon completion of the suction stroke, the pressure in the manifold 2 reaches atmospheric, thereby moving the ball 136 onto the seat 134 and closing off the'aperture 138 by the pressure differential existing between the manifold 2 and the chamber 104.

During the remaining three fourths of the cycle, the vacuum in the chamber 104 is transmitted through the apertures 114, chambers 106 and 108, aperture 116 and conduit 12!) to the diaphragm housing 14 to maintain substantially a constant vacuum in the chamber 28. In this manner, the diaphragm 26 is retained in practically a constant position to maintain the switch 60 in a neutral or open position and preclude a grounding out of the magneto. It will be readily apparent that the limited communication provided by the apertured partitions 112 and 110 and the apertured end plate 118, cooperating with the chambers 106 and 108, will effectively dampen the vacuum changes in the chamber 104 to minimize the effect on the diaphragm 26 of the vacuumchanges or surges created by the engine. It will be appreciated that the previously mentioned manual switch which is interposed in either the wire 68 or wire 72 must be retained in an open position until the engine has attained its normal operating speed and load before the surge tank 100 can be effectively utilized.

Also during the remaining three fourths or non-suction portion of each cycle, a portion of the mixture in the intake manifold 2 is gradually pulled through the conduit 10, bushing 126 and aperture 140 into the chamber 104 l to gradually reduce the vacuum therein. By the beginningo'f the next suction stroke, the previously existing vacuum in the chamber 104 is substantially reduced to reduce the force holding the ball 136 on the seat 134. In this manner; removal the ball 136 from the seat 134 is assured during the next suction stroke of the engine. Furthermore, in the event the engine becomes overloaded, or attempts to run away, the decrease in vacucreated in the manifold 2 will be transmitted through the conduit 10, bushing 126 and aperture 140 to the chamber 104. From the chamber 104, the decreased vacuum is transmitted through the chambers 106 and 108 and conduit 120 tothe diaphragm housing 14, where upon the diaphragm 26 is released for upward movement by the spring 52 in the previously described manner to cutoffthe It will be notd that the bushing 126, including the check valve 135, isi'ei'novable, therefore, the surge tank 160 may be easily and simply converted to a surge tank for use on multi-cyiinder engines if desired. more, the valve'136 may be replaced with any suitable type of check valve (not shown), providing the valve is not spring loaded.

From theforegoing, it is apparent that the present invention provides a novel safety device to prevent an internal combustion engine from becoming overloaded. The device operates upon a decrease in vacuum in the intake manifold, therefore, leaks in the diaphragm, diaphragrn'housing, or in the interconnecting conduit will cause actuation of the device in such a manner to shut down the engine. Itis also apparent that the present invention provides a practical and efiicient safety device which may be economically manufactured, and that the safe operation of isolated internal combustion engine power units will be enhance Changes may be made in the combination and arrangement of parts as heretofore set forth in the specification and shown in the drawings, it being understood that any modification in the precise embodiment of the invention may be made within the scope of the following claims Without departing from the spirit of the invention.

I claim: a

1. A vacuum operated safety device for an internal combustion engine having an intake manifold providing communication between the engine intake valves and a throttle valve and provided with an ignition circuit, comprising a housing, a diaphragm in the housing, a stem secured tojthe diaphragm and extending freely through one side of the housing, a switch electrically connected to the ignition circuit, a switch actuating arm carried by said stern insuch a position to actuate the switch upon movement of the stem and diaphragm, a conduit interconnecting the opposite side of the housing to the intake manifold between the engine intake valves and the butterfly valve toimpose the vacuum in the intake manifold upon one side of the diaphragm and urge the diaphragm Furtherin one direction, a spring connected to said stern for moving the stern and diaphragm in the opposite direction upon a reduction of vacuum in the intake manifold to actuate the switch and interrupt the ignition circuit, a drain valve connected to the cooling system of the engine, a valve member in the valve, and a valve stem connected to the valve member extending into a position adjacent the first mentioned stern in such a manner to move the valve member to an open position upon movement of the first mentioned stem in said opposite direction subsequent to actuation of the switch,

2, A vacuum operated safety device for an internal combustion engine having an intake manifold providing communication between the engine intake valve and a throttle valve and provided with an ignition circuit, comprising a housing, a diaphragm in the housing, an ignition circuit breaking structure operable by the diaphragm, a conduit connecting the housing to the intake manifold between the engine intake valvetand the throttle valve, a baffled surge tank interposed in said conduit to dampen the effeet on the diaphragm of vacuum changes in the intake manifold a check valve in the surge tank arranged to preclude a rapid decrease in vacuum in the housing in a closed position thereof, and passageway means around the check 1 valve in a closed position of the check valve to provide a gradual decrease of vacuum in the housing upon a loss of vacuum in the intake manifold.

3. A vacuum operated safety device for an internal combustion engine having an intake manifold providing communication between the engine intake valve and a throttle valve and provided with an ignition circuit, comprising a housing, a diaphragm in the housing, an ignition circuit breaking structure operable by the diaphragm, a conduit connecting the housing to the intake manifold between the engine intake valve and the throttle valve, a bafiied surge tank interposed in said conduit to dampen the effect on the diaphragm of vacuum changes in the intake manifold, a check valve in the surge tank arranged to preclude a rapid decrease in vacuum in the housing in a closed position thereof, passageway means around the check valve in a closed position of the check valve to provide a gradual decrease of vacuum in the housing upon a loss of vacuum in the intake manifold, and apertured partitions in the surge tank.

References Cited in the file of this patent UNITED STATES PATENTS 

